Fuses, MCB, and RCD, What Do They All Do?

BAOKEZHEN is an independent enterprise who fully operate Research&Development, manufacture, export, pack&transportation, and after-sales service as one-stop solution. We have obtained UL / CUL / ETL / CETL / CE / UKCA / BS / SAA and other international safety certifications. We show you the usage and function of Fuse, MCB and RCD.

 

 

AIKE is an independent enterprise who fully operate Research&Development, manufacture, export, pack&transportation, and after-sales service as one-stop solution. We have obtained UL / CUL / ETL / CETL / CE / UKCA / BS / SAA and other international safety certifications. We show you the usage and function of Fuse, MCB and RCD.

 

Fuses

A fuse is a simple enough device. It is a thin wire that runs between two electrical contacts. When current flows through the wire, it gets hot. If too much current flows through it, it melts, thus breaking the circuit.
This provides basic protection against overload current or overcurrent protection, and it generally protects you from the far greater amount of current needed to blow a fuse. Nor does it protect appliances, which can be damaged beyond repair when a fuse is blown.
What do you do when a removable wire fuse on a fuse panel blows? The first thing to do is find out why it blew, because it indicates a fault somewhere. But to replace it, you need to find the correct fuse rating, pull the fuse, find a screwdriver, reconnect the fuse, and cut the wire using a handy pair of wire cutters.
So fuses don't protect you (only your wiring) and they take some time to have any effect.

 

 

MCB

Enter the MCB or miniature circuit breaker, sometimes colloquially called a trip switch. This little device cleverly uses a solenoid to separate the two contacts if the current exceeds a certain threshold. It has two major advantages.
1. It can be reset by flicking a small plastic switch. Very useful when the bulb has just burned out and tripped the MCB.
2. It responds quickly and reliably. A properly specified MCB should break the circuit within 0.2 to 5 seconds.
If you have a conventional fuse panel, I highly recommend replacing the rewireable fuses with MCBs, as they are inherently safer and more convenient.
However, that's not the whole story. When a device fails or has a problem, it does not necessarily result in overcurrent. This means that your electrical system is perfectly capable of supplying enough current to cause serious injury or death.

 

Australia Twin RCD Plastic Socket with Switch

 

RCD

RCDs (Residual Current Devices) are designed to protect people, not the wiring.RCDs monitor the power on the fire and zero wires. If all goes well, the amount of current on the fire wire should be exactly the same as the amount of current returned from the neutral wire, which means zero current on the ground wire.
However, if some current in the fire wire leaks to the ground wire, or leaks out completely, this indicates a fault. In this case, the RCD will detect the difference in current between the fire and zero wires and respond within a fraction of a second and completely cut the circuit. 

Current building regulations and British Standards state that an RCD should be fitted in almost all cases when installing a new circuit, and in practice there are very few cases where a new circuit does not require RCD protection, all in the name of protecting human life.
We strongly recommend that you install RCDs on certain critical equipment, particularly powerful showers and any external sockets. Power showers can become fatal if they fail, immediately making the water supply active; an RCD will solve this problem immediately and at minimal cost. After installation, you can sleep easy knowing you have a modern, reliable electrical installation that will protect you from harm in any situation.

Double Plastic RCD socket with switch

 

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